The present invention relates to a composition comprising (A) at least one organosiloxane resin having an average of at least two silicon-bonded hydrogen groups per molecule; (B) at least one polyene having an average of at least two non-aromatic carbon-carbon double bonds per molecule; and (C) a catalyst. Methods for preparing the above-described composition are also disclosed.
Compositions have been previously described which have been prepared by reacting Sixe2x80x94H containing linear polysiloxanes, cyclosiloxanes, and/or tetrahedral siloxysilanes with polyenes. While these compositions had certain useful properties, at high temperatures they tended to degrade and their glass transition temperature (Tg) and modulus values were either too high resulting in stress-induced failures in die-attach adhesive and coating applications or too low resulting in poor adhesive strength and scratch or mar resistance. The present invention utilizes an organosiloxane resin containing silicon-bonded hydrogen groups which when reacted with a polyene having non-aromatic carbon-carbon double bonds provides a reaction product with improved thermal stability as well as Tg and modulus values that are attractive for low stress die attach applications.
The present invention relates to a composition comprising (A) at least one organosiloxane resin having an average of at least two silicon-bonded hydrogen groups per molecule; (B) at least one polyene having an average of at least two non-aromatic carbon-carbon double bonds per molecule; and (C) a catalyst. Methods for preparing the above-described composition are also disclosed.